NEWFOUNDLAND APPALACHIANS 



207 



Pennsylvanian System 



A body of coarse elastics, the Barachois series, rests on the Mississip- 

 pian Codroy series in the St. George Bay area. It consists of 5000 or more 

 feet of coarse conglomerate, sandstone, arkose, and shale, with some thin 

 coal beds, presumably all continental, and indicates a new sharp uplift 

 nearby. No other Pennsylvanian strata are known in Newfoundland. 



INTRUSIONS 



Serpentine Belts 



Two belts of ultrabasic plutons occur in Newfoundland. They are 

 known as the eastern and the western serpentine belts. Not only serpen- 

 tine but also chromite are common associates of the basic intrusions 

 (Snelgrove, 1934). The principal rocks are peridotite, pyroxenite, and 

 gabbro. See map, Fig. 13.4. 



The eastern serpentine belt extends from Carmanville to the head- 

 waters of the Gander Biver. Serpentine masses are exposed intermittently 

 over 120 miles in a general northeast-southwest direction. According to 

 Snelgrove: 



This part of the island is relatively low-lying and is characterized by undu- 

 lating topography. The ultrabasic rocks of this belt, in contrast with those on 

 the west coast, are only partly exhumed by erosion and consequently lack any 

 striking topographic expression. The serpentines form low, bare ridges, with 

 few prominent peaks or knolls. 



At the north tip, it has an outcrop width of one-half mile, and dips westward. 

 Highly serpentinized dunite is confined to a band varying from one hundred to 

 five hundred feet in width, flanked by pyroxenite. The serpentine band forms 

 small prominences. The country rocks beneath the intrusives are chloritized vol- 

 canics, locally fragmental, underlain by micaceous black slate and quartzite. 

 Above the ultrabasic rocks are black slate, gray quartzitic sandstones, and con- 

 glomerate. These sedimentary and volcanic rocks are probably of early Paleo- 

 zoic age; they appear to have been intruded conformably by the plutonic rocks. 



The section of the belt exposed near the headwaters of the Gander River, 

 central Newfoundland, consists of serpentinized dunite with lenticular segre- 

 gations of medium-grained to pegmatitic pyroxenite. Its width was not deter- 

 mined. Structurally, the intrusion appears to be nearly vertical; it is invaded by 

 a granite batholith lying to the south and east. 



The Western Serpentine Belt consists of a series of four main intrusions, 

 which seem to have been injected concordantly at different horizons into a 



Fig. 13.4. Ultramafic plutons of Newfoundland. Reproduced from Snelgrove, 1938. 



folded sedimentary and volcanic series (Humber Arm series), probably of 

 upper Ordovician age, which underlies this part of the lowland of the west 

 coast of Newfoundland. 



South of Bay of Islands, the eastern section of this belt, as exposed in Blow- 

 me-down Mountain, is a pseudo-stratified complex and is composed ol a wide 

 zone of various types of peridotites at the base, succeeded by more siliceous 

 rocks toward the top. Both the intrusives and the country rocks of sandstones, 

 slates, argillites, and lavas have a general westward dip near Blow-me-down 

 Mountain. In the section south of Bay of Islands, a lopolithic structure is indi- 

 cated. Five miles to the east of the southernmost intrusive ol the western belt 

 is a satellitic serpentine mass containing an asbestos prospect. The structural 



